Methods of preparing a catalyst

ABSTRACT

A method comprising a) calcining a silica support at temperature in the range of from about 100° C. to about 500° C. to form a precalcined silica support; b) contacting the precalcined silica support with a titanium alkoxide to form a titanated support; c) subsequent to b), contacting the titanated support with a polyol to form a polyol associated titanated support (PATS); d) contacting at least one of the silica support, pre-calcined silica support, the titanated support, the PATS, or combinations thereof with a chromium-containing compound to form a polymerization catalyst precursor; e) drying the polymerization catalyst precursor to form a dried polymerization catalyst precursor; and f) calcining the dried polymerization catalyst precursor to produce a polymerization catalyst, wherein less than about 0.1 wt. % of a highly reactive volatile organic compound (HRVOC) is emitted during the calcining of the dried polymerization catalyst precursor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 14/699,533 filed Apr. 29, 2015 and entitled“Methods of Preparing a Catalyst,” which is incorporated by referenceherein in its entirety.

TECHNICAL FIELD

The present disclosure relates to catalyst compositions. Morespecifically, the present disclosure relates to methods of preparingolefin polymerization catalyst compositions.

BACKGROUND

Enhancements in preparation methods for olefin polymerization catalystscan reduce the costs associated with catalyst production and improveprocess economics. For example, during catalyst production, materialssuch as highly reactive volatile organic compounds (HRVOC) may beemitted. HRVOCs play a role in the formation of ozone in ozonenonattainment areas, i.e., areas that do not meet the EnvironmentalProtection Agency's air quality standards for ground-level ozone.Consequently, processes that result in the production of HRVOCs may besubject to compliance with various state and federal regulationsregarding HRVOC emission, such as the HRVOC emissions cap and tradeprogram (HECT). Thus, there is an ongoing need to develop improvedprocesses for the production of catalysts that result in decreased HRVOCemissions.

SUMMARY

A method comprising a) calcining a silica support at temperature in therange of from about 100° C. to about 500° C. to form a precalcinedsilica support; b) contacting the precalcined silica support with atitanium alkoxide to form a titanated support; c) subsequent to b),contacting the titanated support with a polyol to form a polyolassociated titanated support (PATS); d) contacting at least one of thesilica support, pre-calcined silica support, the titanated support, thePATS, or combinations thereof with a chromium-containing compound toform a polymerization catalyst precursor; e) drying the polymerizationcatalyst precursor to form a dried polymerization catalyst precursor;and f) calcining the dried polymerization catalyst precursor to producea polymerization catalyst, wherein less than about 0.1 wt. % of a highlyreactive volatile organic compound (HRVOC) is emitted during thecalcining of the dried polymerization catalyst precursor.

A method comprising a) calcining a silica support at temperature in therange of from about 100° C. to about 500° C. to form a precalcinedsilica support; b) contacting the precalcined silica support with atitanium alkoxide to form a titanated support; c) subsequent to b),contacting the titanated support with a polyol to form a polyolassociated titanated support (PATS); d) contacting the PATS with achromium-containing compound to form a polymerization catalystprecursor; e) drying the polymerization catalyst precursor to form adried polymerization catalyst precursor; and f) calcining the driedpolymerization catalyst precursor to produce a polymerization catalyst,wherein less than about 0.1 wt. % of a highly reactive volatile organiccompound (HRVOC) is emitted during the calcining of the driedpolymerization catalyst precursor.

A method comprising a) calcining a silica support at temperature in therange of from about 100° C. to about 500° C. to form a precalcinedsilica support; b) contacting the precalcined silica support with achromium-containing compound to form a Cr/silica support; c) contactingthe Cr/silica support with a titanium alkoxide to form a titanatedsupport; d) subsequent to c), contacting the titanated support with apolyol to form a polymerization catalyst precursor; e) drying thepolymerization catalyst precursor to form a dried polymerizationcatalyst precursor; and f) calcining the dried polymerization catalystprecursor to produce a polymerization catalyst, wherein less than about0.1 wt. % of a highly reactive volatile organic compound (HRVOC) isemitted during the calcining of the dried polymerization catalystprecursor.

A method comprising a) calcining a silica support at temperature in therange of from about 100° C. to about 500° C. to form a precalcinedsilica support; b) contacting the precalcined silica support with atitanium alkoxide to form a titanated support; c) contacting thetitanated support with a chromium-containing compound to form a Cr/Tisupport; d) subsequent to c), contacting the Cr/Ti support with a polyolto form a polymerization catalyst precursor; e) drying thepolymerization catalyst precursor to form a dried polymerizationcatalyst precursor; and f) calcining the dried polymerization catalystprecursor to produce a polymerization catalyst, wherein less than about0.1 wt. % of a highly reactive volatile organic compound (HRVOC) isemitted during the calcining of the dried polymerization catalystprecursor.

A method comprising a) calcining a Cr/silica support at temperature inthe range of from about 100° C. to about 500° C. to form a precalcinedsupport; b) contacting the precalcined support with a titanium alkoxideto form a titanated support; c) subsequent to b), contacting thetitanated support with a polyol to form a polyol associated titanatedsupport (PATS); d) drying the PATS to form a dried polymerizationcatalyst precursor; and e) calcining the dried polymerization catalystprecursor to produce a polymerization catalyst, wherein less than about0.1 wt. % of a highly reactive volatile organic compound (HRVOC) isemitted during the calcining of the dried polymerization catalystprecursor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-5 are thermogravimetric/mass spectra for the samples fromExample 2.

DETAILED DESCRIPTION

Disclosed herein are methods for the preparation of a polymerizationcatalyst. In an embodiment, the method comprises contacting asilica-support material and a titanium-containing compound to form atitanated support, and subsequent thereto contacting the titanatedsupport with a polyol to form a polyol associated titanated support(PATS). Chromium may be added to the support (e.g., the PATS) at anysuitable time during the method via contact of the support with achromium-containing compound, thereby yielding a polymerization catalystprecursor. The polymerization catalyst precursor may be heat-treated andduring heat treatment the amount of HRVOCs emitted may be less than theamount emitted during heat treatment of an otherwise similar materialformed in the absence of a polyol. The methodologies disclosed hereinresult in a catalyst whose preparation has a reduced emission of HRVOCsand are herein designated reduced emissions catalysts (RECs).Embodiments of various specific method sequences of contacting thecatalyst components to yield the PATS and/or the RECs are disclosed inmore detail herein.

In an embodiment, a silica-support material (e.g., silica support)suitable for use in the present disclosure may have a surface area andpore volume effective to provide for the production of an activecatalyst (e.g., a REC). In an embodiment, the silica-support materialpossesses a surface area in the range of from about 10 m²/gram to about1000 m²/gram, alternatively from about 100 m²/gram to about 700 m²/gram,alternatively from about 200 m²/gram to about 600 m²/gram, oralternatively from about 250 m²/gram to about 550 m²/gram. Thesilica-support material may be further characterized by a pore volume ofgreater than about 0.5 cm³/gram, alternatively greater than about 0.9cm³/gram, alternatively greater than about 1.1 cm³/gram, oralternatively greater than about 1.5 cm³/gram. In an embodiment, thesilica-support material is characterized by a pore volume ranging fromabout 0.5 cm³/gram to about 1.5 cm³/gram. The silica-support materialmay be further characterized by an average particle size of from about10 microns to about 500 microns, alternatively about 25 microns to about300 microns, or alternatively about 40 microns to about 150 microns.Generally, the average pore size of the silica-support material rangesfrom about 10 Angstroms to about 1000 Angstroms. In one embodiment, theaverage pore size of the silica-support material is in the range of fromabout 50 Angstroms to about 500 Angstroms, while in yet anotherembodiment the average pore size ranges from about 75 Angstroms to about350 Angstroms.

The silica-support material may contain greater than about 50 percent(%) silica, alternatively greater than about 80% silica, alternativelygreater than about 90% silica by weight of the silica-support material.The silica-support material may be prepared using any suitable method,for example the silica-support material may be prepared synthetically byhydrolyzing tetrachlorosilane (SiCl₄) with water or by contacting sodiumsilicate with a mineral acid. An example of silica-support materialsuitable for use in this disclosure includes without limitation ES70which is a silica-support material with a surface area of 300 m²/g, anda pore volume of 1.6 cc/g that is commercially available from PQCorporation. The silica-support material may include additionalcomponents that do not adversely affect the REC, such as zirconia,alumina, thoria, magnesia, fluoride, sulfate, phosphate, or mixturesthereof.

The silica-support material may be present in the REC in an amount offrom about 50 weight percent (wt. %) to about 99 wt. %, or alternativelyfrom about 80 wt. % to about 99 wt. %. Herein the percentage of supportrefers to the final weight percent of support associated with thecatalyst by total weight of the catalyst after all processing steps.

In an embodiment, the titanium-containing compound comprises atetravalent titanium (Ti⁴⁺)-containing compound. The Ti⁴⁺-containingcompound may be any compound that comprises tetravalent titanium,alternatively the Ti⁴⁺-containing compound may be any compound that issoluble in an aqueous solution and able to release a Ti⁴⁺ species intosolution. In an embodiment, the titanium-containing compound is anorganotitanium containing at least one alkoxide. Alternatively, thetitanium-containing compound comprises a titanium tetraalkoxide. In anembodiment, the titanium alkoxide is titanium isopropoxide Ti(OiPr)₄,titanium ethoxide Ti(OEt)₄, titanium n-propoxide Ti(nOPr)₄, titaniumbutoxide Ti(OBu)₄, titanium 2-ethylhexoxide, or combinations thereof.

The amount of titanium present in the REC may range from about 0.1 wt. %to about 10 wt. % titanium by weight of the REC, alternatively fromabout 0.5 wt. % to about 5 wt. % titanium, alternatively from about 0.1wt. % to about 4 wt. %, or alternatively from about 2 wt. % to about 4wt. %. Herein the percentage titanium refers to the final weight percenttitanium associated with the catalyst composition by total weight of thecatalyst composition after all processing steps.

In various embodiments, the silica-support material andtitanium-containing compound are pre-contacted in the absence of apolyhydric alcohol (e.g., a polyalcohol or polyol) to form a titanatedsupport, and the polyol is subsequently contacted with the titanatedsupport. In some embodiments, the polyol can comprise any hydrocarbonhaving at least 2 alcohol groups (or alternatively called hydroxygroups); alternatively, at least 3 alcohol groups; or alternatively, atleast 4 alcohol groups. In an embodiment, the polyol is an aliphatichydrocarbon comprising at least two alcohol groups. In some embodiments,the polyol is a glycol, a sugar, a reduced sugar, an oligomer of aglycol, or combinations thereof.

In an aspect, the polyol can be an aliphatic polyol such as ethyleneglycol, diethylene glycol, triethylene glycol, tetraethylene glycol,tripropylene glycol, polyethylene glycols with a molecular weight offrom 106 to 8500, polyethylene glycols with a molecular weight of from400 to 2000, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol,1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol,1,2-hexanediol, 1,6-hexanediol, 1,2-octanediol, 1,8-octanediol,1,2-decanediol, 1,10-decanediol, glycerol, 2,2-dimethylolpropane,trimethylolethane, trimethylolpropane, pentaerythritol,dipentaerythritol, sorbitol, 1,2,4-butanetriol,2,2,4-trimethyl-1,3-pentanediol, or combinations thereof.

In an aspect, the polyol can be a cyclic aliphatic polyol such as1,2-cyclopentanediol, 1,3-cyclopentanediol, 1,2-cyclohexanediol,1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol,1,4-cyclohexanedimethanol, bis(4-hydroxycyclohexyl)methane,2,2-bis(4-hydroxy-cyclohexyl)propane, or any combination thereof.

In an aspect, the polyol can be an aralkyl polyol such as1-phenyl-1,2-ethanediol, 1,2-benzenedimethanol, 1,3-benzene-di-methanol,1,4-benzene-dimethanol, or mixtures thereof. In an aspect, the polyolcan be an aromatic polyol such as 1,2-benzenediol (pyrocatechol),1,3-benzenediol (resorcinol), 1,4-benzenediol, methyl catechol, methylresorcinol, 1,2,4-benzenetriol, 2-hydroxybenzylalcohol,3-hydroxybenzylalcohol, 4-hydroxybenzylalcohol,3,5-dihydroxybenzylalcohol, 2-(2-hydroxyphenyl)ethanol,2-(3-hydroxy-phenyl)-ethanol, 2-(4-hydroxyphenyl)-ethanol,2-phenyl-1,2-propanediol or mixtures thereof.

In an embodiment, the polyol is a sugar alcohol which refers to thehydrogenated forms of the aldoses or ketoses of a sugar. For example,glucitol, also known as sorbitol, has the same linear structure as thechain form of glucose, but the aldehyde (—CHO) group is replaced with a—CH₂OH group. Other common sugar alcohols include the monosaccharideserythritol and xylitol and the disaccharides lactitol and maltitol.

Generally, sugar alcohols can be characterized by the general formulaHO—CH₂—(CH—OH)_(n)—CH₂—OH, wherein n is typically from 1 to 22. Forexample, when n=2, the sugar alcohol can be erythritol, threitol, etc.For example, when n=3, the sugar alcohol can be arabitol, xylitol,ribitol, etc. For example, when n=4, the sugar alcohol can be mannitol,sorbitol, etc. The most common sugar alcohols have 5 or 6 carbon atomsin their structure; wherein n is 3 or 4, respectively. In an embodiment,the sugar alcohol comprises mannitol, sorbitol, arabitol, threitol,xylitol, ribitol, galactitol, fruitol, iditol, inositol, volemitol,isomalt, malitol, lactitol, or combinations thereof.

In an embodiment, the polyol comprises ethylene glycol, diethyleneglycol, triethylene glycol, tetraethylene glycol, tripropylene glycol,polyethylene glycols with a molecular weight of from 106 to 1000,1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol,1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-hexanediol,1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol,1,2-octanediol, 1,8-octanediol, 1,2-decanediol, 1,10-decanediol,glycerol, 2,2-dimethylolpropane, trimethylolethane, trimethylolpropane,pentaerythritol, dipentaerythritol, sorbitol, 1,2,4-butanediol,2,2,4-trimethyl-1,3-pentanediol, 1-phenyl-1,2-ethanediol,1,2-benzenediol (pyrocatechol), 1,3-benzenediol (resorcinol),1,4-benzenediol, methyl catechol, methyl resorcinol, 1,2,4-benzenetriol,2-hydroxybenzylalcohol, 3-hydroxybenzylalcohol, 4-hydroxybenzylalcohol,3,5-dihydroxybenzylalcohol, 1,2-benzenedimethanol,1,3-benzenedimethanol, 1,4-benzenedimethanol,2-(2-hydroxyphenyl)ethanol, 2-(3-hydroxyphenyl)ethanol,2-(4-hydroxyphenyl)ethanol, 2-phenyl-1,2-propanediol, bisphenol A(2,2-di(4-hydroxyphenyl)propane), bisphenol F(bis(4-hydroxyphenyl)methane), bisphenol S(4,4′-dihydroxydiphenylsulfone), bisphenol Z(4,4′-cyclohexylidenebisphenol), bis(2-hydroxyphenyl)methane, orcombinations thereof. In an embodiment, the polyol is selected from thegroup consisting of ethylene glycol, glycerol, propylene glycol, butaneglycol, lactic acid or combinations thereof.

In an embodiment, the polyol is present in an amount sufficient toprovide from about 0.1 to about 10 molar equivalents of polyol per moleof titanium, alternatively from about 0.5 to about 5, alternatively fromabout 1 to about 4, or alternatively from about 2 to about 4.

In various embodiments, chromium can be added to the support (to yield aREC comprising chromium) via contact of the silica-support material withone or more chromium-containing compounds. The chromium-containingcompound may be a water-soluble compound or a hydrocarbon-solublecompound. Examples of water-soluble chromium compounds include chromiumtrioxide, chromium acetate, chromium nitrate, or combinations thereof.Examples of hydrocarbon-soluble chromium compounds include tertiarybutyl chromate, a diarene chromium (0) compound, biscyclopentadienylchromium(II), chromium (III) acetylacetonate, or combinations thereof.In one embodiment, the chromium-containing compound may be a chromium(II) compound, chromium (III) compound, or combinations thereof.Suitable chromium (III) compounds include, but are not limited to,chromium carboxylates, chromium naphthenates, chromium halides, chromiumsulfate, chromium nitrate, chromium dionates, or combinations thereof.Specific chromium (III) compounds include, but are not limited to,chromium (III) sulfate, chromium (III) chloride, chromium (III) nitrate,chromic bromide, chromium (III) acetylacetonate, chromium (III) acetate.Suitable chromium (II) compounds include, but are not limited to,chromous chloride, chromous bromide, chromous iodide, chromium (II)sulfate, chromium (II) acetate, or combinations thereof.

The amount of chromium present in the catalyst may range from about 0.1wt. % to about 10 wt. % by weight of the REC, alternatively from about0.25 wt. % to about 3 wt. %, or alternatively from about 0.5 wt. % toabout 1.5 wt. %. Herein, the percentage chromium refers to the finalpercent chromium associated with the support material by total weight ofthe material after all processing steps.

In an embodiment, a method of preparing a REC of the type disclosedherein comprises contacting a silica-support material with atitanium-containing compound to form a titanated support prior tocontact of the titanated support with a polyol. Chromium can be added atany suitable time or step of the method by contacting the support with achromium-containing compound. The silica-support material may be used asprepared or as obtained from commercial sources. Alternatively, thesilica-support material may be calcined prior to utilization in thepreparation of a REC (e.g., prior to contact with any of the othercatalyst components such as titanium alkoxide, polyol, and/orchromium-containing compound). For example, the silica-support materialmay be calcined at a temperature of from about 100° C. to about 500° C.,alternatively from about 125° C. to about 300° C., or alternatively fromabout 150° C. to about 200° C. for a time period of from about 30minutes to about 24 hours, alternatively from about 1 hour to about 12hours, or alternatively from about 1 hour to about 8 hours to produce aprecalcined silica-support material. Hereinafter, the disclosure willrefer to the use of a precalcined silica-support material although it isto be understood that silica-support material may or may not have beensubjected to a precalcination procedure of the type disclosed herein.

In an embodiment, the precalcined silica-support material is contactedwith a titanium containing compound, both of the type disclosed herein,to produce a titanated silica support. The contacting may be carried outusing any suitable method, for example, via ion-exchange, incipientwetness, pore fill, aqueous impregnation, organic solvent impregnation,melt coating, co-gelling, and the like. The titanated silica supportmaterial may subsequently be contacted with a polyol (e.g., ethyleneglycol) to produce a polyol associated titanated silica support (PATS).Contacting of the titanated silica-support material and polyol may becarried out in the presence of any suitable solvent. For example, thesolvent may be an anhydrous organic solvent. In an embodiment, thesolvent comprises alcohols, ketones, aliphatic hydrocarbons, aromatichydrocarbons, halocarbons, ethers, acetonitrile, esters, or combinationsthereof. Alternatively the solvent comprises alcohols, ketones, esters,or combinations thereof.

Aliphatic hydrocarbons which can be useful as a solvent include C₃ toC₂₀ aliphatic hydrocarbons; alternatively, C₄ to C₁₅ aliphatichydrocarbons; or alternatively, C₅ to C₁₀ aliphatic hydrocarbons. Thealiphatic hydrocarbons can be cyclic or acyclic and/or can be linear orbranched, unless otherwise specified. Non-limiting examples of suitableacyclic aliphatic hydrocarbon solvents that can be utilized singly or inany combination include propane, iso-butane, n-butane, butane (n-butaneor a mixture of linear and branched C₄ acyclic aliphatic hydrocarbons),pentane (n-pentane or a mixture of linear and branched C₅ acyclicaliphatic hydrocarbons), hexane (n-hexane or mixture of linear andbranched C₆ acyclic aliphatic hydrocarbons), heptane (n-heptane ormixture of linear and branched C₇ acyclic aliphatic hydrocarbons),octane (n-octane or a mixture of linear and branched C₈ acyclicaliphatic hydrocarbons), and combinations thereof. Aromatic hydrocarbonswhich can be useful as a solvent include C₆ to C₂₀ aromatichydrocarbons; or alternatively, C₆ to C₁₀ aromatic hydrocarbons.Non-limiting examples of suitable aromatic hydrocarbons that can beutilized singly or in any combination in the present disclosure includebenzene, toluene, xylene (including ortho-xylene, meta-xylene,para-xylene, or mixtures thereof), and ethylbenzene, or combinationsthereof.

Halogenated aliphatic hydrocarbons which can be useful as a solventinclude C₁ to C₁₅ halogenated aliphatic hydrocarbons; alternatively, C₁to C₁₀ halogenated aliphatic hydrocarbons; or alternatively, C₁ to C₅halogenated aliphatic hydrocarbons. The halogenated aliphatichydrocarbons can be cyclic or acyclic and/or can be linear or branched,unless otherwise specified. Non-limiting examples of suitablehalogenated aliphatic hydrocarbons which can be utilized includemethylene chloride, chloroform, carbon tetrachloride, dichloroethane,trichloroethane, and combinations thereof; alternatively, methylenechloride, chloroform, dichloroethane, trichloroethane, and combinationsthereof. Halogenated aromatic hydrocarbons which can be useful as asolvent include C₆ to C₂₀ halogenated aromatic hydrocarbons; oralternatively, C₆ to C₁₀ halogenated aromatic hydrocarbons. Non-limitingexamples of suitable halogenated aromatic hydrocarbons includechlorobenzene, dichlorobenzene, and combinations thereof.

Esters, ketones, or alcohols which can be useful as a solvent include C₁to C₂₀, esters, ketones, or alcohols; alternatively, C₁ to C₁₀ esters,ketones, aldehydes, or alcohols; or alternatively, C₁ to C₅ esters,ketones, aldehydes, or alcohols. Non-limiting examples of suitableesters which can be utilized as a solvent include ethyl acetate, propylacetate, butyl acetate, isobutyl isobutyrate, methyl lactate, ethyllactate, and combinations thereof. Non-limiting examples of suitableketones which can be utilized as a solvent include acetone, ethyl methylketone, methyl isobutyl ketone, and combinations thereof. Non-limitingexamples of suitable alcohols which can be utilized as a solvent includemethanol, ethanol, propanol, isopropanol, n-butanol, isobutanol,pentanol, hexanol, heptanol, octanol, benzyl alcohol, phenol,cyclohexanol, and the like, or combinations thereof. In an embodiment,the solvent comprises methanol, ethanol, isopropanol, propanol, butanol,acetone, methylethylketone, ethyl acetate, heptane, or combinationsthereof.

In an embodiment, the method further comprises drying the PATS. Forexample the PATS may be dried at a temperature of from about 40° C. toabout 300° C., alternatively from about 80° C. to about 200° C., oralternatively from about 100° C. to about 200° C. for a time period offrom about 30 min to about 24 hours, or alternatively from about 1 hourto about 12 hours to form a dried PATS. In an embodiment, the dried PATSis subsequently contacted with the chromium-containing compound to forma chromium-containing PATS. Contacting of the dried PATS with thechromium-containing compound may be carried out using any suitablemethodology such as incipient wetness impregnation for example. In anembodiment, the chromium-containing PATS (e.g., catalyst precursor) isactivated to form the REC. In alternative embodiments, the chromium maybe added to the support (and the resultant catalyst, e.g.,polymerization catalyst) at any suitable time in the overall catalystproduction process. For example, in alternative embodiments, thechromium may be added by contacting at least one of a silica support, apre-calcined silica support, a titanated support, a PATS, orcombinations thereof with a chromium-containing compound.

In some embodiments, a method of forming a REC comprises contacting aprecalcined silica-support material with a chromium-containing compoundto form a chromium-containing silica support material. The resultingchromium-containing silica-support material may then be contacted with atitanium-containing compound to form a Cr/Ti/Si material. The Cr/Ti/Simaterial may be dried to form a dried Cr/Ti/Si material under conditionssimilar to those disclosed herein for drying a PATS. The dried Cr/Ti/Simaterial may be contacted with a polyol in the presence of a solvent toform a chromium-containing PATS (e.g., a catalyst precursor) which cansubsequently be activated to form a REC.

In an embodiment, a methodology for formation of a REC comprisescontacting of the titanium-containing compound and silica-supportmaterial prior to the addition of a polyol.

In an embodiment, the chromium-containing PATS is heat treated (e.g.,calcined) to form a REC. Heat treatment of the chromium-containing PATSmay be carried out using any suitable method, e.g., fluidization.Without wishing to be limited by theory, heat treatment of thechromium-containing support may result in an increase in the amount ofhexavalent chromium present in the catalyst. In an embodiment, heattreatment of the chromium-containing PATS is carried out in any suitableatmosphere, such as air, oxygen, inert gases (e.g., Ar), or carbonmonoxide by heating to a temperature of from about 400° C. to about1000° C., alternatively from about 500° C. to about 900° C.,alternatively from about 550° C. to about 850° C., or alternatively fromabout 550° C. to about 750° C. Heat treatment may be carried out for aperiod of time ranging from about 30 minutes to about 24 hours,alternatively from about 1 hour to about 12 hours, or alternatively fromabout 4 hours to about 8 hours.

In an embodiment, one or more of the steps described previously hereinfor the preparation of a REC may be carried out in a reactor or reactorsystem. In an alternative embodiment, one or more of the steps describedpreviously herein for the preparation of a REC may be carried outoutside of a reactor or reactor system. In such embodiments, one or morepreparation parameters (e.g., heat treatment of the chromium-containingPATS) may be adjusted to facilitate formation of the REC. The resultingmaterial is a REC which may function as a polymerization catalyst whenemployed in a polymerization reaction/system.

The catalysts of the present disclosure (i.e., RECs) are suitable foruse in any olefin polymerization method, using various types ofpolymerization reactors. In an embodiment, a polymer of the presentdisclosure is produced by any olefin polymerization method, usingvarious types of polymerization reactors. As used herein,“polymerization reactor” includes any reactor capable of polymerizingolefin monomers to produce homopolymers and/or copolymers. Homopolymersand/or copolymers produced in the reactor may be referred to as resinand/or polymers. The various types of reactors include, but are notlimited to those that may be referred to as batch, slurry, gas-phase,solution, high pressure, tubular, autoclave, or other reactor and/orreactors. Gas phase reactors may comprise fluidized bed reactors orstaged horizontal reactors. Slurry reactors may comprise vertical and/orhorizontal loops. High pressure reactors may comprise autoclave and/ortubular reactors. Reactor types may include batch and/or continuousprocesses. Continuous processes may use intermittent and/or continuousproduct discharge or transfer. Processes may also include partial orfull direct recycle of un-reacted monomer, un-reacted comonomer,catalyst and/or co-catalysts, diluents, and/or other materials of thepolymerization process.

Polymerization reactor systems of the present disclosure may compriseone type of reactor in a system or multiple reactors of the same ordifferent type, operated in any suitable configuration. Production ofpolymers in multiple reactors may include several stages in at least twoseparate polymerization reactors interconnected by a transfer systemmaking it possible to transfer the polymers resulting from the firstpolymerization reactor into the second reactor. Alternatively,polymerization in multiple reactors may include the transfer, eithermanual or automatic, of polymer from one reactor to subsequent reactoror reactors for additional polymerization. Alternatively, multi-stage ormulti-step polymerization may take place in a single reactor, whereinthe conditions are changed such that a different polymerization reactiontakes place.

The desired polymerization conditions in one of the reactors may be thesame as or different from the operating conditions of any other reactorsinvolved in the overall process of producing the polymer of the presentdisclosure. Multiple reactor systems may include any combinationincluding, but not limited to multiple loop reactors, multiple gas phasereactors, a combination of loop and gas phase reactors, multiple highpressure reactors or a combination of high pressure with loop and/or gasreactors. The multiple reactors may be operated in series or inparallel. In an embodiment, any arrangement and/or any combination ofreactors may be employed to produce the polymer of the presentdisclosure.

According to one embodiment, the polymerization reactor system maycomprise at least one loop slurry reactor. Such reactors arecommonplace, and may comprise vertical or horizontal loops. Monomer,diluent, catalyst system, and optionally any comonomer may becontinuously fed to a loop slurry reactor, where polymerization occurs.Generally, continuous processes may comprise the continuous introductionof a monomer, a catalyst, and/or a diluent into a polymerization reactorand the continuous removal from this reactor of a suspension comprisingpolymer particles and the diluent. Reactor effluent may be flashed toremove the liquids that comprise the diluent from the solid polymer,monomer and/or comonomer. Various technologies may be used for thisseparation step including but not limited to, flashing that may includeany combination of heat addition and pressure reduction; separation bycyclonic action in either a cyclone or hydrocyclone; separation bycentrifugation; or other appropriate method of separation.

Typical slurry polymerization processes (also known as particle-formprocesses) are disclosed in U.S. Pat. Nos. 3,248,179, 4,501,885,5,565,175, 5,575,979, 6,239,235, 6,262,191 and 6,833,415, for example;each of which are herein incorporated by reference in their entirety.

Suitable diluents used in slurry polymerization include, but are notlimited to, the monomer being polymerized and hydrocarbons that areliquids under reaction conditions. Examples of suitable diluentsinclude, but are not limited to, hydrocarbons such as propane,cyclohexane, isobutane, n-butane, n-pentane, isopentane, neopentane, andn-hexane. Some loop polymerization reactions can occur under bulkconditions where no diluent is used. An example is polymerization ofpropylene monomer as disclosed in U.S. Pat. No. 5,455,314, which isincorporated by reference herein in its entirety.

According to yet another embodiment, the polymerization reactor maycomprise at least one gas phase reactor. Such systems may employ acontinuous recycle stream containing one or more monomers continuouslycycled through a fluidized bed in the presence of the catalyst underpolymerization conditions. A recycle stream may be withdrawn from thefluidized bed and recycled back into the reactor. Simultaneously,polymer product may be withdrawn from the reactor and new or freshmonomer may be added to replace the polymerized monomer. Such gas phasereactors may comprise a process for multi-step gas-phase polymerizationof olefins, in which olefins are polymerized in the gaseous phase in atleast two independent gas-phase polymerization zones while feeding acatalyst-containing polymer formed in a first polymerization zone to asecond polymerization zone. One type of gas phase reactor is disclosedin U.S. Pat. Nos. 4,588,790, 5,352,749, and 5,436,304, each of which isincorporated by reference in its entirety herein.

According to still another embodiment, a high pressure polymerizationreactor may comprise a tubular reactor or an autoclave reactor. Tubularreactors may have several zones where fresh monomer, initiators, orcatalysts are added. Monomer may be entrained in an inert gaseous streamand introduced at one zone of the reactor. Initiators, catalysts, and/orcatalyst components may be entrained in a gaseous stream and introducedat another zone of the reactor. The gas streams may be intermixed forpolymerization. Heat and pressure may be employed appropriately toobtain optimal polymerization reaction conditions.

According to yet another embodiment, the polymerization reactor maycomprise a solution polymerization reactor wherein the monomer iscontacted with the catalyst composition by suitable stirring or othermeans. A carrier comprising an organic diluent or excess monomer may beemployed. If desired, the monomer may be brought in the vapor phase intocontact with the catalytic reaction product, in the presence or absenceof liquid material. The polymerization zone is maintained attemperatures and pressures that will result in the formation of asolution of the polymer in a reaction medium. Agitation may be employedto obtain better temperature control and to maintain uniformpolymerization mixtures throughout the polymerization zone. Adequatemeans are utilized for dissipating the exothermic heat ofpolymerization.

Polymerization reactors suitable for the present disclosure may furthercomprise any combination of at least one raw material feed system, atleast one feed system for catalyst or catalyst components, and/or atleast one polymer recovery system. Suitable reactor systems for thepresent disclosure may further comprise systems for feedstockpurification, catalyst storage and preparation, extrusion, reactorcooling, polymer recovery, fractionation, recycle, storage, loadout,laboratory analysis, and process control.

Conditions that are controlled for polymerization efficiency and toprovide polymer properties include, but are not limited to temperature,pressure, type and quantity of catalyst or co-catalyst, and theconcentrations of various reactants. Polymerization temperature canaffect catalyst productivity, polymer molecular weight and molecularweight distribution. Suitable polymerization temperatures may be anytemperature below the de-polymerization temperature, according to theGibbs Free Energy Equation. Typically, this includes from about 60° C.to about 280° C., for example, and/or from about 70° C. to about 110°C., depending upon the type of polymerization reactor and/orpolymerization process.

Suitable pressures will also vary according to the reactor andpolymerization process. The pressure for liquid phase polymerization ina loop reactor is typically less than 1000 psig (6.9 MPa). Pressure forgas phase polymerization is usually at about 200 psig (1.4 MPa)-500 psig(3.45 MPa). High pressure polymerization in tubular or autoclavereactors is generally run at about 20,000 psig (138 MPa); to 75,000 psig(518 MPa). Polymerization reactors can also be operated in asupercritical region occurring at generally higher temperatures andpressures. Operation above the critical point of a pressure/temperaturediagram (supercritical phase) may offer advantages.

The concentration of various reactants can be controlled to producepolymers with certain physical and mechanical properties. The proposedend-use product that will be formed by the polymer and the method offorming that product may be varied to determine the desired finalproduct properties. Mechanical properties include, but are not limitedto tensile strength, flexural modulus, impact resistance, creep, stressrelaxation and hardness tests. Physical properties include, but are notlimited to density, molecular weight, molecular weight distribution,melting temperature, glass transition temperature, temperature melt ofcrystallization, density, stereoregularity, crack growth, short chainbranching, long chain branching and rheological measurements.

The concentrations of monomer, co-monomer, hydrogen, co-catalyst,modifiers, and electron donors are generally important in producingspecific polymer properties. Comonomer may be used to control productdensity. Hydrogen may be used to control product molecular weight.Co-catalysts may be used to alkylate, scavenge poisons and/or controlmolecular weight. The concentration of poisons may be minimized, aspoisons may impact the reactions and/or otherwise affect polymer productproperties. Modifiers may be used to control product properties andelectron donors may affect stereoregularity.

Polymers such as polyethylene homopolymers and copolymers of ethylenewith other mono-olefins may be produced in the manner described aboveusing the RECs prepared as described herein. Polymer resins produced asdisclosed herein may be formed into articles of manufacture or end usearticles using techniques known in the art such as extrusion, blowmolding, injection molding, fiber spinning, thermoforming, and casting.For example, a polymer resin may be extruded into a sheet, which is thenthermoformed into an end use article such as a container, a cup, a tray,a pallet, a toy, or a component of another product. Examples of otherend use articles into which the polymer resins may be formed includepipes, films, bottles, fibers, and so forth.

In an embodiment, a REC prepared as disclosed herein results in areduction in the level of HRVOCs produced during the catalystpreparation. For example, the HRVOCs may comprise hydrocarbons, aromaticcompounds, alcohols, ketones, or combinations thereof. In an embodiment,the HRVOCs comprise alkenes, alternatively propylene, butene, ethylene,or combinations thereof. RECs produced as disclosed herein may becharacterized by HRVOC emissions that are reduced by from about 50% toabout 99% when compared to the emissions from an otherwise similarcatalyst prepared in the absence of a polyol. Alternatively, emissionsof HRVOCs from RECs prepared as disclosed herein are reduced by greaterthan about 50%, alternatively greater than about 75%, alternativelygreater than about 90%, or alternatively greater than about 99% whereincompared to an otherwise similar catalyst prepared in the absence of apolyol. In an embodiment, HRVOCs emissions during preparation of RECs ofthe type disclosed herein are less than about 1 wt. % based on the totalweight of the catalyst, alternatively less than about 0.5 wt. %, oralternatively less than about 0.1 wt. %. In an embodiment, the HRVOC ispropylene and the REC has emissions of from about 50 wt. % to about 1wt. % based on the weight percent of titanium in the REC, alternativelyless than about 20 wt. %, alternatively less than about 10 wt. %, oralternatively less than about 1 wt. %.

EXAMPLES

The following examples are given as particular embodiments of thedisclosure and to demonstrate the practice and advantages thereof. It isunderstood that the examples are given by way of illustration and arenot intended to limit the specification or the claims to follow in anymanner.

The high load melt index (HLMI) of a polymer resin represents the rateof flow of a molten resin through an orifice of 0.0825 inch diameterwhen subjected to a force of 21,600 grams at 190° C. The HLMI values aredetermined in accordance with ASTM D1238 condition E.

Polymerizations were performed in 1.2 L isobutane at 100° C. and 550 psiof ethylene with 5 mL of 1-hexene and run to a productivity of 3200 gPE/g catalyst. The catalyst activity was determined by dividing the massof polymer recovered from the reaction by the active polymerizationtime.

Example 1

Four catalysts were prepared and the effects of the presence of polyolduring preparation on the catalyst properties were investigated. Variousproperties of the catalysts of the present disclosure, designated S1-S4,are compared to that of a control catalyst, designated CONT, prepared inthe absence of a polyol in Table 1.

TABLE 1 Titanium Catalyst Source Additive Activity HLMI Solvent CONTTi(OiPr)₄ None 5767 18.4 MeOH S1 Ti(OiPr)₄ 1 equiv. 5455 20.4 MeOHglycerol S2 Ti(OiPr)₄ 3 equiv. 6226 20.6 iPrOH glycerol S3 Ti(OiPr)₄ 3equiv. 6067 18.9 iPrOH EG S4 Ti(OiPr)₄ 3 equiv 4695 19.9 MeOH EG EG =ethylene glycol, MeOH = methanol, iPrOH = isopropanol

The results demonstrate the catalysts prepared with a polyol (i.e.,RECs) do not appear to be significantly different in terms ofpolymerization activity or the melt index potential of the polymersproduced when compared to the results observed when using a controlcatalyst prepared in the absence of a polyol.

Example 2

The emissions of HRVOCs for catalysts of the type disclosed herein(RECs) were investigated. Specifically, thermogravimetric and massspectral analysis (TGA/MS) of catalysts of the type disclosed hereinprepared in the presence or absence of a polyol were carried out. FIG. 1depicts the TGA/MS spectrum of a Cr/silica-titania catalyst preparedwith Ti(OiPr)₄ in the absence of a polyol (CONT). Referring to FIG. 1,on the right side of the figure there is a peak at ˜250° C. frommass-to-charge ratio (m/z) signals of 39, 41, and 42 indicating theemission of propylene. FIG. 2 depicts the TGA/MS spectrum of acommercial Cr/silica catalyst that had been wetted with isopropanol,which from ˜85° C. to 165° C. had peaks at m/z of 31, 39, 41, 42, 43,and 45. These results demonstrate that the signal observed in FIG. 1 isfrom propylene and not due to the loss of isopropanol from silica-boundtitania.

S1, which was a REC prepared in the presence of the polyol glycerol, andthe solvent methanol, displayed what appeared to be a significantdecrease in propylene production, see FIG. 3. The TGA/MS spectrumpresented in FIG. 3 displays two losses of isopropanol. The first lossoccurred at about 70° C. and the second occurred at about 130° C.Without wishing to be limited by theory, the results suggest the firstpeak is likely due to the evaporation of free solvent while the secondpeak appears due to the loss of isopropanol physically adsorbed to thesilica gel. A third broad peak, of much weaker intensity, occurred ataround 225° C. and was comprised mainly of signals of m/z=39, 41, and 42suggesting this was propylene.

A second catalyst was prepared using 3 equivalents of glycerol andisopropanol as a solvent, S2. A TGA/MS spectrum of S2, FIG. 4, showsthere are only two peaks before combustion of the organics, one at 145°C. corresponding to desorption of isopropanol and another at almost 300°C. The latter peak was comprised of signals of m/z=42, 43, and possibly44, 45; however, this peak is shouldered on the peak for CO₂ that ispresent due to combustion of the organics. The observed signals areconsistent with glycerol, which has a boiling point of 290° C., andthere does not appear to be anything in the spectrum to suggest theproduction of propylene. The results indicate that glycerol is capableof replacing the isopropoxide ligands at titanium.

Similar results were observed when ethylene glycol was used in place ofglycerol. The addition of three equivalents of the diol in both methanoland isopropanol, samples S3 and S4, respectively, resulted inundetectable amounts of propylene during TGA/MS analysis, see FIG. 5. Inthe TGA/MS spectra of the catalyst prepared in methanol, S3, isopropanoldesorption is observed at about 150° C. followed by a peak at about 270°C. containing signals of m/z=43 and 44 which might be attributable toethylene glycol. There did not however appear to be any sign ofpropylene production in the spectrum. Similar results were obtained whenthe catalyst was prepared in isopropanol.

The following are enumerated embodiments are provided as non-limitingexamples:

A first embodiment which is a method comprising a) calcining a silicasupport at temperature in the range of from about 100° C. to about 500°C. to form a precalcined silica support; b) contacting the precalcinedsilica support with a titanium alkoxide to form a titanated support; c)subsequent to b), contacting the titanated support with a polyol to forma polyol associated titanated support (PATS); d) contacting at least oneof the silica support, pre-calcined silica support, the titanatedsupport, the PATS, or combinations thereof with a chromium-containingcompound to form a polymerization catalyst precursor; e) drying thepolymerization catalyst precursor to form a dried polymerizationcatalyst precursor; and f) calcining the dried polymerization catalystprecursor to produce a polymerization catalyst, wherein less than about0.1 wt. % of a highly reactive volatile organic compound (HRVOC) isemitted during the calcining of the dried polymerization catalystprecursor.

A second embodiment which is the method of the first embodiment whereinthe polyol comprises ethylene glycol, diethylene glycol, triethyleneglycol, tetraethylene glycol, tripropylene glycol, polyethylene glycolswith a molecular weight of from 106 to 1000, 1,2-propanediol,1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol,1,5-pentanediol, neopentyl glycol, 1,2-hexanediol, 1,6-hexanediol,1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-octanediol,1,8-octanediol, 1,2-decanediol, 1,10-decanediol, glycerol,2,2-dimethylolpropane, trimethylolethane, trimethylolpropane,pentaerythritol, dipentaerythritol, sorbitol, 1,2,4-butanediol,2,2,4-trimethyl-1,3-pentanediol, 1-phenyl-1,2-ethanediol,1,2-benzenediol (pyrocatechol), 1,3-benzenediol (resorcinol),1,4-benzenediol, methyl catechol, methyl resorcinol, 1,2,4-benzenetriol,2-hydroxybenzylalcohol, 3-hydroxybenzylalcohol, 4-hydroxybenzylalcohol,3,5-dihydroxybenzylalcohol, 1,2-benzenedimethanol,1,3-benzenedimethanol, 1,4-benzenedimethanol,2-(2-hydroxyphenyl)ethanol, 2-(3-hydroxyphenyl)ethanol,2-(4-hydroxyphenyl)ethanol, 2-phenyl-1,2-propanediol, bisphenol A(2,2-di(4-hydroxyphenyl)propane), bisphenol F(bis(4-hydroxyphenyl)methane), bisphenol S(4,4′-dihydroxydiphenylsulfone), bisphenol Z(4,4′-cyclohexylidenebisphenol), bis(2-hydroxyphenyl)methane, orcombinations thereof.

A third embodiment which is the method of any of the first throughsecond embodiments wherein the polyol is present in an amount of fromabout 0.1 to about 10 molar equivalents per mole of titanium.

A fourth embodiment which is the method of any of the first throughfourth embodiments wherein the HRVOC is an alkene compound.

A fifth embodiment which is the method of the fourth embodiment whereinthe alkene compound is propylene.

A sixth embodiment which is the method of any of the first through fifthembodiments wherein an emission of the HRVOC is reduced by from about50% to about 100% when compared to the emission of the HRVOC from apolymerization catalyst prepared by an otherwise similar process in theabsence of the polyol.

A seventh embodiment which is the method of any of the first throughsixth embodiments wherein the titanium alkoxide is a titaniumtetra-alkoxide.

An eighth embodiment which is the method of any of the first throughseventh embodiments wherein the titanium alkoxide comprises titaniumisopropoxide.

A ninth embodiment which is the method of any of the first througheighth embodiments wherein the titanium alkoxide is present in an amountof from about 0.1 wt. % to about 10 wt. %.

A tenth embodiment which is the method of any of the first through ninthembodiments wherein the chromium-containing compound is added to thesilica support.

An eleventh embodiment which is a method comprising contacting thepolymerization catalyst produced by the method of the first embodimentwith an olefin monomer in a reaction zone under conditions suitable toproduce a polymer; and recovering the polymer.

A twelfth embodiment which is the method of the eleventh embodimentwherein the olefin monomer comprises ethylene and the polymer comprisespolyethylene.

A thirteenth embodiment which is the method of any of the elevenththrough twelfth embodiments wherein the reactor is a loop reactor.

A fourteenth embodiment which is a method comprising a) calcining asilica support at temperature in the range of from about 100° C. toabout 500° C. to form a precalcined silica support; b) contacting theprecalcined silica support with a titanium alkoxide to form a titanatedsupport; c) subsequent to b), contacting the titanated support with apolyol to form a polyol associated titanated support (PATS); d)contacting the PATS with a chromium-containing compound to form apolymerization catalyst precursor; e) drying the polymerization catalystprecursor to form a dried polymerization catalyst precursor; and f)calcining the dried polymerization catalyst precursor to produce apolymerization catalyst, wherein less than about 0.1 wt. % of a highlyreactive volatile organic compound (HRVOC) is emitted during thecalcining of the dried polymerization catalyst precursor.

A fifteenth embodiment which is the method of the fourteenth embodimentwherein the polyol comprises ethylene glycol, diethylene glycol,triethylene glycol, tetraethylene glycol, tripropylene glycol,polyethylene glycols with a molecular weight of from 106 to 1000,1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol,1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-hexanediol,1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol,1,2-octanediol, 1,8-octanediol, 1,2-decanediol, 1,10-decanediol,glycerol, 2,2-dimethylolpropane, trimethylolethane, trimethylolpropane,pentaerythritol, dipentaerythritol, sorbitol, 1,2,4-butanediol,2,2,4-trimethyl-1,3-pentanediol, 1-phenyl-1,2-ethanediol,1,2-benzenediol (pyrocatechol), 1,3-benzenediol (resorcinol),1,4-benzenediol, methyl catechol, methyl resorcinol, 1,2,4-benzenetriol,2-hydroxybenzylalcohol, 3-hydroxybenzylalcohol, 4-hydroxybenzylalcohol,3,5-dihydroxybenzylalcohol, 1,2-benzenedimethanol,1,3-benzenedimethanol, 1,4-benzenedimethanol,2-(2-hydroxyphenyl)ethanol, 2-(3-hydroxyphenyl)ethanol,2-(4-hydroxyphenyl)ethanol, 2-phenyl-1,2-propanediol, bisphenol A(2,2-di(4-hydroxyphenyl)propane), bisphenol F(bis(4-hydroxyphenyl)methane), bisphenol S(4,4′-dihydroxydiphenylsulfone), bisphenol Z(4,4′-cyclohexylidenebisphenol), bis(2-hydroxyphenyl)methane, orcombinations thereof.

A sixteenth embodiment which is the method of any of the fourteenththrough fifteenth embodiments wherein the polyol is present in an amountof from about 0.1 to about 10 molar equivalents per mole of titanium.

A seventeenth embodiment which is the method of any of the fourteenththrough sixteenth embodiments wherein the HRVOC is hydrocarbons,aromatic compounds, alcohols, ketones, or combinations thereof.

An eighteenth embodiment which is the method of the seventeenthembodiment wherein the HRVOC is propylene.

A nineteenth embodiment which is the method of any of the fourteenththrough eighteenth embodiments wherein an emission of the HRVOC isreduced by from about 50% to about 100% when compared to the emission ofthe HRVOC from a polymerization catalyst prepared by an otherwisesimilar process in the absence of the polyol.

A twentieth embodiment which is the method of the eighteenth embodimentwherein propylene emissions range from about 50 wt. % to about less than1 wt. % based on the weight percent titanium.

A twenty-first embodiment which is the method of any of the fourteenththrough twentieth embodiments wherein the titanium isopropoxide ispresent in an amount of from about 0.1 wt. % to about 10 wt. %.

A twenty-second embodiment which is a method comprising a) calcining asilica support at temperature in the range of from about 100° C. toabout 500° C. to form a precalcined silica support; b) contacting theprecalcined silica support with a chromium-containing compound to form aCr/silica support; c) contacting the Cr/silica support with a titaniumalkoxide to form a titanated support; d) subsequent to c), contactingthe titanated support with a polyol to form a polymerization catalystprecursor; e) drying the polymerization catalyst precursor to form adried polymerization catalyst precursor; and f) calcining the driedpolymerization catalyst precursor to produce a polymerization catalyst,wherein less than about 0.1 wt. % of a highly reactive volatile organiccompound (HRVOC) is emitted during the calcining of the driedpolymerization catalyst precursor.

A twenty-third embodiment which is a method comprising a) calcining asilica support at temperature in the range of from about 100° C. toabout 500° C. to form a precalcined silica support; b) contacting theprecalcined silica support with a titanium alkoxide to form a titanatedsupport; c) contacting the titanated support with a chromium-containingcompound to form a Cr/Ti support; d) subsequent to c), contacting theCr/Ti support with a polyol to form a polymerization catalyst precursor;e) drying the polymerization catalyst precursor to form a driedpolymerization catalyst precursor; and f) calcining the driedpolymerization catalyst precursor to produce a polymerization catalyst,wherein less than about 0.1 wt. % of a highly reactive volatile organiccompound (HRVOC) is emitted during the calcining of the driedpolymerization catalyst precursor.

A twenty-fourth embodiment which is a method comprising a) calcining aCr/silica support at temperature in the range of from about 100° C. toabout 500° C. to form a precalcined support; b) contacting theprecalcined support with a titanium alkoxide to form a titanatedsupport; c) subsequent to b), contacting the titanated support with apolyol to form a polyol associated titanated support (PATS); d) dryingthe PATS to form a dried polymerization catalyst precursor; and e)calcining the dried polymerization catalyst precursor to produce apolymerization catalyst, wherein less than about 0.1 wt. % of a highlyreactive volatile organic compound (HRVOC) is emitted during thecalcining of the dried polymerization catalyst precursor.

While various embodiments have been shown and described, modificationsthereof can be made by one skilled in the art without departing from thespirit and teachings of the disclosure. The embodiments described hereinare exemplary only, and are not intended to be limiting. Many variationsand modifications of the disclosure disclosed herein are possible andare within the scope of the disclosure. Where numerical ranges orlimitations are expressly stated, such express ranges or limitationsshould be understood to include iterative ranges or limitations of likemagnitude falling within the expressly stated ranges or limitations(e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than0.10 includes 0.11, 0.12, 0.13, etc.). Use of the term “optionally” withrespect to any element of a claim is intended to mean that the subjectelement is required, or alternatively, is not required. Bothalternatives are intended to be within the scope of the claim. Use ofbroader terms such as comprises, includes, having, etc. should beunderstood to provide support for narrower terms such as consisting of,consisting essentially of, comprised substantially of, etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present disclosure. Thus, the claims are a further description andare an addition to the embodiments of the present disclosure. Thediscussion of a reference in the disclosure is not an admission that itis prior art to the present disclosure, especially any reference thatmay have a publication date after the priority date of this application.The disclosures of all patents, patent applications, and publicationscited herein are hereby incorporated by reference, to the extent thatthey provide exemplary, procedural or other details supplementary tothose set forth herein.

What is claimed is:
 1. A pre-catalyst composition comprising (i) aprecalcined silica support, (ii) a tetravalent titanium compound, (iii)a polyol, and (iv) a chromium-containing compound.
 2. The composition ofclaim 1 wherein the precalcined silica support is characterized by asurface area of from about 250 m²/g to about 1000 m²/g and a pore volumeof greater than about 1.0 cm³/g.
 3. The composition of claim 1 whereinthe tetravalent titanium compound comprises a titanium tetra-alkoxide.4. The composition of claim 3 wherein the titanium tetra-alkoxidecomprises titanium ethoxide, titanium n-propoxide, titaniumisopropoxide, titanium butoxide or combinations thereof.
 5. Thecomposition of claim 1 wherein the tetravalent titanium compound ispresent in an amount of from about 0.1 wt % to about 10 wt % based onthe total weight of the composition.
 6. The composition of claim 1wherein the polyol comprises ethylene glycol, diethylene glycol,triethylene glycol, tetraethylene glycol, tripropylene glycol,polyethylene glycols with a molecular weight of from 106 to 1000,1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol,1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-hexanediol,1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol,1,2-octanediol, 1,8-octanediol, 1,2-decanediol, 1,10-decanediol,glycerol, 2,2-dimethylolpropane, trimethylolethane, trimethylolpropane,pentaerythritol, dipentaerythritol, sorbitol, 1,2,4-butanediol,2,2,4-trimethyl-1,3-pentanediol, 1-phenyl-1,2-ethanediol,1,2-benzenediol (pyrocatechol), 1,3-benzenediol (resorcinol),1,4-benzenediol, methyl catechol, methyl resorcinol, 1,2,4-benzenetriol,2-hydroxybenzylalcohol, 3-hydroxybenzylalcohol, 4-hydroxybenzylalcohol,3,5-dihydroxybenzylalcohol, 1,2-benzenedimethanol,1,3-benzenedimethanol, 1,4-benzenedimethanol,2-(2-hydroxyphenyl)ethanol, 2-(3-hydroxyphenyl)ethanol,2-(4-hydroxyphenyl)ethanol, 2-phenyl-1,2-propanediol, bisphenol A(2,2-di(4-hydroxyphenyl)propane), bisphenol F(bis(4-hydroxyphenyl)methane), bisphenol S(4,4′-dihydroxydiphenylsulfone), bisphenol Z(4,4′-cyclohexylidenebisphenol), bis(2-hydroxyphenyl)methane, orcombinations thereof.
 7. The composition of claim 1 wherein the polyolis present in an amount of from about 0.1 to about 10 molar equivalentsper mole of tetravalent titanium compound.
 8. The composition of claim 1wherein the chromium-containing compound comprises basic chromiumacetate.
 9. The composition of claim 1 wherein the chromium-containingcompound is present in an amount of from about 0.1 wt. % to about 10 wt.% by total weight of the composition.
 10. A pre-catalyst compositionprepared by: a) calcining a silica support at temperature in the rangeof from about 100° C. to about 500° C. to form a precalcined silicasupport; b) contacting the precalcined silica support in a solvent witha titanium alkoxide to form a titanated support; c) subsequent to b),contacting the titanated support with a polyol to form a polyolassociated titanated support (PATS); and d) contacting at least one ofthe silica support, the pre-calcined silica support, the titanatedsupport, the PATS, or combinations thereof with a chromium-containingcompound to form the pre-catalyst composition.
 11. The composition ofclaim 10 wherein the solvent is anhydrous.
 12. The composition of claim11 wherein the solvent comprises alcohols, ketones, aliphatichydrocarbons, aromatic hydrocarbons, halocarbons, ethers, acetonitrile,esters, or combinations thereof.
 13. A pre-catalyst compositioncomprising (i) a titania-coated silica support, (ii) a polyol, (iii) and(iv) a chromium-containing compound, wherein the titania-coated silicasupport comprises a tetravalent titanium-containing compound selectedfrom the group consisting of titanium ethoxide, titanium n-propoxide,titanium isopropoxide, titanium butoxide or combinations thereof. 14.The composition of claim 13 wherein the titania-coated silica support ischaracterized by a surface area of from about 250 m²/g to about 1000m²/g and a pore volume of greater than about 1.0 cm³/g.
 15. Thecomposition of claim 13 wherein the polyol comprises ethylene glycol,diethylene glycol, triethylene glycol, tetraethylene glycol,tripropylene glycol, polyethylene glycols with a molecular weight offrom 106 to 1000, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol,1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol,1,2-hexanediol, 1,6-hexanediol, 1,2-cyclohexanediol,1,4-cyclohexanediol, 1,2-octanediol, 1,8-octanediol, 1,2-decanediol,1,10-decanediol, glycerol, 2,2-dimethylolpropane, trimethylolethane,trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol,1,2,4-butanediol, 2,2,4-trimethyl-1,3-pentanediol,1-phenyl-1,2-ethanediol, 1,2-benzenediol (pyrocatechol), 1,3-benzenediol(resorcinol), 1,4-benzenediol, methyl catechol, methyl resorcinol,1,2,4-benzenetriol, 2-hydroxybenzylalcohol, 3-hydroxybenzylalcohol,4-hydroxybenzylalcohol, 3,5-dihydroxybenzylalcohol,1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol,2-(2-hydroxyphenyl)ethanol, 2-(3-hydroxyphenyl)ethanol,2-(4-hydroxyphenyl)ethanol, 2-phenyl-1,2-propanediol, bisphenol A(2,2-di(4-hydroxyphenyl)propane), bisphenol F(bis(4-hydroxyphenyl)methane), bisphenol S(4,4′-dihydroxydiphenylsulfone), bisphenol Z(4,4′-cyclohexylidenebisphenol), bis(2-hydroxyphenyl)methane, orcombinations thereof.
 16. The composition of claim 15 wherein the polyolis present in an amount of from about 0.1 to about 10 molar equivalentsper mole of the tetravalent titanium-containing compound.
 17. Thecomposition of claim 13 wherein the chromium-containing compoundcomprises basic chromium acetate present in an amount of from about 0.1wt. % to about 10 wt. % by total weight of the composition.
 18. Apre-catalyst composition comprising (i) a titania-coated silica support,(ii) a polyol, and (iii) a chromium-containing compound, wherein thermaltreatment of the pre-catalyst composition produces less than about 1 wt.% of highly reactive volatile chemicals based on the total weight of thecomposition.
 19. The composition of claim 18, wherein the titania-coatedsilica support comprises a tetravalent titanium-containing compoundselected from the group consisting of titanium ethoxide, titaniumn-propoxide, titanium isopropoxide, titanium butoxide or combinationsthereof.
 20. The composition of claim 18 wherein the highly reactivevolatile organic compound comprises propylene.